“Estimates of freshwater fish extinctions during the twentieth century are conservative, because it can take 20-50 years to confirm extinction,” explains lead author, Noel Burkhead, a research fish biologist for the U.S. Geological Survey (USGS), in a press release.

image: David Starr Jordan.

Burkhead calculated that the rate of freshwater fish extinction on the continent is at least 877 times faster than in the fossil record, where a freshwater fish vanished every three million years or so on average.

Currently, 1,213 freshwater fish are found in North America.

Over the last century, fish have been pushed to extinction by dams, pollution, invasive species, channelization of rivers and other impacts.

A scientist in 2009 calculated that freshwater species were currently four to six more likely to go extinct than their marine and land relatives. For decades, scientists have warned that the earth may soon (or already) be facing a mass extinction due to human impacts.

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